The Ecological Role of a Proteolytic Psychrophile, Flavobacterium limicola Belonging to the Cytophaga-Flavobacteria Cluster, in the Decomposition of Particulate Organic Nitrogen in Freshwater Sediment

  • Tamaki Hideyuki
    Institute of Applied Biochemistry, University of Tsukuba Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST)
  • Hanada Satoshi
    Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST)
  • Nakamura Kazunori
    Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST)
  • Nomura Nakao
    Institute of Applied Biochemistry, University of Tsukuba
  • Matsumura Masatoshi
    Institute of Applied Biochemistry, University of Tsukuba
  • Kamagata Yoichi
    Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST)

Bibliographic Information

Other Title
  • Ecological Role of a Proteolytic Psychrophile Flavobacterium limicola Belonging to the Cytophaga Flavobacteria Cluster in the Decomposition of Particulate Organic Nitrogen in Freshwater Sediment

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Abstract

Microbes of the Cytophaga-Flavobacterium (CF) group, within the phylum Bacteroidetes, have been considered contributors to the early decomposition of particulate organic matter (POM) in sediments because of their abundance in the ecosystem and their great ability to degrade macromolecules on artificial media. However, there is no report on the ability of members of this group to decompose POM in sediment. We investigated the POM-decomposition capabilities of members of the CF group, Flavobacterium limicola strains ST-82T, ST-10 and ST-92 isolated from freshwater sediment as proteolytic psychrophiles, in sterilized sediment slurries. All strains of F. limicola grew and survived at over 108 cfu per ml for more than 30 days in the sediment slurries at 5°C. Protease activity levels in the slurries inoculated with the strains were 3-5 times higher than the control level for over 30 days of incubation at 5°C. Concentrations of total dissolved nitrogen (TDN) released by the hydrolysis of particulate organic nitrogen (PON), significantly increased only in the slurries inoculated with F. limicola strains. Approximately 70-80% of the TDN released was converted to NH4+-N in these inoculated slurries. The results clearly demonstrate that F. limicola strains ST-82T, ST-10 and ST-92 are able to secrete an extracellular protease and hydrolyze PON to TDN and thereby mineralize TDN to NH4+-N in freshwater sediment. This is the first report on the decomposition and mineralization of PON by members of the CF group in benthic environments.<br>

Journal

  • Microbes and Environments

    Microbes and Environments 19 (2), 147-153, 2004

    Japanese Society of Microbial Ecology / Japanese Society of Soil Microbiology / Taiwan Society of Microbial Ecology / Japanese Society of Plant Microbe Interactions / Japanese Society for Extremophiles

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